THE POLAR ONSET AND DEVELOPMENT OF THE NOVEMBER 8 AND 9, 1991, GLOBALRED AURORA

On November 8, 1991, a major magnetic storm began with a sudden commen cement at 0647 UT; it continued until about 1800 UT on November 9. Ass ociated with this storm there was a great aurora which continued throu gh November 8 and until at least 1200 UT on November 9. The first opti cal indication of this event was the appearance of bright sun-aligned arcs over Eureka, North West Territories (89 degrees corrected geomagn etic latitude (CGM)), Canada from 0750 UT until about 1230 UT on Novem ber 8. By that time, there was a gradual transformation to dominant 63 00 Angstrom emission over the central polar cap. Gradually, the major soft electron precipitation and associated red aurora moved equatorwar d. The aurora reached a low-latitude limit of 40 degrees CGM at 0600 U T on November 9. The polar arcs reached 22 kR intensity (5577 Angstrom ), while the red aurora seen later at low latitudes was at least 100 k R (6300 Angstrom). The analysis of Defense Meteorological Satellite Pr ogram (DMSP) particle data from 83 passes during November 8 and 9 show ed the extent and movement of precipitation from the polar region to m idlatitudes. A comparison of this event was made with the earlier grea t auroral event of March 13-14, 1989. While the extent in low latitude and the duration of the two disturbances were similar, the November 8 -9 event had approximately one half of the total energy input into the ionosphere. Its striking and unusual feature was the auroral onset an d activity in the central polar region, a feature possibly related to the solar wind interplanetary magnetic field orientation.